Document feeder for an image forming apparatus

ABSTRACT

A document feeder of an image forming apparatus includes a guide that arranges a width of a recording medium. A recording medium pickup module picks up the recording medium. A recording medium pickup module shifting unit shifts the recording medium pickup module in association with the movement of the guide. The recording medium pickup module includes a guide rack connected to the guide at one end. A pinion unit supports reciprocating motion of the guide rack. A pickup rack engaged with the pinion unit linearly reciprocates in parallel with the guide rack, and is connected to the recording medium pickup module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2006-3466, filed Jan. 12, 2006, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a document feeder of an image forming apparatus. More particularly, the present invention relates to a document feeder of an image forming apparatus adapted to shift a recording medium pickup module in association with operation of a guide unit that arranges a width of a recording medium.

2. Description of the Related Art

Generally, image forming apparatuses, for example, inkjet printers, multi-function peripherals, and laser beam printers, have a document feeder for supplying a recording medium into a main body of the apparatus. The document feeder includes a recording medium guide mounted to a paper feeding cassette or a paper feeding tray for stacking therein plural sheets of the recording medium to arrange and settle the recording medium as stacked. The recording medium guide arranges and settles various types of recording medium according to size, and guides the recording medium so that the recording medium can be fed without being skewed.

FIG. 1 shows a conventional automatic document feeder (ADF).

Referring to FIG. 1, an ADF 1 includes a recording medium width controlling guide 30 reciprocating in directions of arrows A and B along a shaft 20. The shaft 20, being made of metal, is transmitted with power from a driving part and rotated by a gear (not shown) connected to one side thereof.

A recording medium pickup module 40 is mounted to the other side of the shaft 20, that is, the opposite side to the recording medium width controlling guide 30. Upon being transmitted with power from the driving part, the shaft 20 is rotated. As accordingly rotated, a pickup roller 41 of the recording medium pickup module 40 picks up and feeds the recording medium to a paper feeding roller (not shown). Below the pickup roller 41 of the recording medium pickup module 40, a buckler 43 is provided to separate the recording medium sheets picked up by the pickup roller 41 so that the recording medium can be fed to the paper feeding roller sheet by sheet.

A fixing arm 35 is formed at one side of the recording medium width controlling guide 30 to fit around the shaft 20. A guide body 32 is integrally formed with the fixing arm 35 to area-contact with a frame 10 in a sliding manner. A projection constituting a first fixing projection unit (not shown) is formed on a bottom surface of the guide member 32. A handle 34 is formed on an upper part of the guide member 32. A plurality of projections constituting a second fixing projection unit 11 are formed on the frame 10 along a mounting direction of the shaft 20 to correspond to movement of the first fixing projection unit.

When using the above-structured conventional ADF I of an image forming apparatus, to easily stack the recording medium into an inkjet printer or a multifunction peripheral, a user holds the handle 34 of the guide body 32 of the recording medium width controlling guide 30 with one hand, moves the recording medium width controlling guide 30 in the direction B by a distance a little greater than a width of the recording medium, and releases the recording medium width controlling guide 30 from a force applied. Therefore, the first fixing projection unit of the recording medium width controlling guide 30 is serratedly meshed with the second fixing projection unit 11 of the frame 10, thereby being moved by the guide body 32 in the direction B. Then, plural sheets of the recording medium are stacked in the frame 10 constructing a recording medium support. Next, the user holds and moves the handle 34 of the guide body 32 of the recording medium width controlling guide 30 with one hand in the direction A as much as the width of the recording medium. Accordingly, the first fixing projection unit of the recording medium width controlling guide 30 is serratedly meshed again with projections of the second fixing projection unit 11 of the frame 10 and moved in the direction A. Therefore, the recording medium width controlling guide 30 is restricted in vertical movement by the fixing arm 35 moving along the shaft 20 and horizontal movement by the serration mesh between the first fixing projection unit and the second fixing projection unit 11. As a result, the recording medium can be fixed between a guide surface of the recording medium width controlling guide 30 and a guide reference surface 45 of the frame 10.

When a printing command is transmitted from an external device, such as a personal computer (PC), through a control unit of the image forming apparatus, the shaft 20 is rotated by the gear connected with the driving motor and accordingly, the pickup roller 41 connected to the shaft 20 is rotated, thereby picking up and feeding the stacked recording medium toward the buckler 43. The recording medium fed to the buckler 43 keeps being fed by the paper feeding roller and printed with images or texts by a print head that jets ink.

However, in the conventional ADF 1 as described above, because the recording medium pickup module 40 that picks up the recording medium is mounted inclined to one side, a force for picking up the recording medium may be unevenly applied so that the recording medium may be obliquely or skewedly fed.

Accordingly, a need exists for an image forming apparatus having an improved document feeder that moves a recording medium pickup module in association with the operation of a recording medium width controlling guide.

SUMMARY OF THE INVENTION

Accordingly, an aspect of the present invention is to provide a document feeder for an image forming apparatus adapted to shift a recording medium pickup module in association with operation of a recording medium width controlling guide that arranges a width of the recording medium to maintain a more optimum positioning of the recording medium pickup module corresponding to the width of the recording medium.

A document feeder of an image forming apparatus according to exemplary embodiments of the present invention includes a guide that arranges a width of a recording medium. A recording medium pickup module picks up the recording medium. A recording medium pickup module shifting unit shifts the recording medium pickup module in association with movement of the guide.

The recording medium pickup module includes a guide rack connected to the guide by one end. A pinion unit supports a reciprocating motion of the guide rack. A pickup rack engaged with the pinion unit linearly reciprocates in parallel with the guide rack, and is connected to the recording medium pickup module.

The guide rack and the pickup rack are moved in the same direction as each other. The pickup rack is moved by half a distance as much as a moving distance of the guide rack.

The pinion unit includes a first gear wheel having a predetermined pitch circle diameter, and a second gear wheel having a pitch circle diameter half of the predetermined pitch circle diameter of the first gear wheel. An intermediate gear is connected to the second gear wheel and has a pitch circle diameter substantially the same as the pitch circle diameter of the second gear wheel.

The first gear wheel is connected with the guide rack, and the intermediate gear is connected with the pickup rack.

The document feeder may further include a driving motor that drives the recording medium pickup module. A motor shaft is connected to the driving motor. A pickup module shaft is connected with the recording medium pickup module for transmission of a rotational force from the motor and connected to the motor shaft to linearly move with respect to the motor shaft.

The motor shaft is formed as a hollow pipe having a groove formed on an inner circumference in a lengthwise direction. The pickup module shaft is movably inserted in the motor shaft and has a projection corresponding to the groove.

The recording medium pickup module is placed in the middle of width of the recording medium.

Other objects, advantages, and salient features of the invention will become apparent from the detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The above aspect and other exemplary features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawing figures, wherein;

FIG. 1 is a perspective view showing a structure of a document feeder in a conventional image forming apparatus;

FIG. 2 is a perspective view of a document feeder of an image forming apparatus, according to an exemplary embodiment of the present invention;

FIG. 3 is a side elevational view of FIG. 2 seen in a direction of arrow II;

FIG. 4 is a top plan view of FIG. 2 seen in a direction of arrow III; and

FIG. 5 is an enlarged perspective view of portion B of FIG. 2.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawing figures.

In the following description, the matters defined in the description, such as a detailed construction and elements thereof, are provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention may be carried out without those defined matters. Also, well-known functions and constructions are omitted to provide a clear and concise specification.

FIG. 2 is a perspective view showing a structure of a document feeder for an image forming apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a document feeder 100 includes a guide 110 for arranging a width of a recording medium stacked in a recording medium supply tray 101. A recording medium pickup module 130 picks up and feeds the recording medium (not shown) stacked in the recording medium supply tray 101. A recording medium pickup module shifting unit 150 shifts the recording medium pickup module 130 in association with operation of the guide 110.

The recording medium pickup module shifting unit 150 includes a guide rack 151 connected to the guide 110 at one end. A pinion unit 153 supports reciprocating motion of the guide rack 151. A pickup rack 155 is connected with the pinion unit 153 and linearly reciprocates corresponding to the guide rack 151.

FIG. 3 is a side elevational view of FIG. 2 in an arrowed direction II. FIG. 4 is a top plan view of FIG. 2 in an arrowed direction III.

As shown in FIGS. 3 and 4, the pinion unit 153 includes first and second gear wheels 153 a and 153 b, and an intermediate gear 153 d. In an exemplary implementation, a first pitch circle diameter D1 of the first gear wheel 153 a is greater than a second pitch circle diameter D2 of the second gear wheel 153 b. In an exemplary implementation, the first pitch circle diameter D1 is twice as much as the second pitch circle diameter D2. In an exemplary implementation, a third pitch circle diameter D3 of the intermediate gear 153 d is the same as the second pitch circle diameter D2 of the second gear wheel 153 b.

The first gear wheel 153 a is connected to the guide rack 151. The second gear wheel 153 b is connected above the -first gear wheel 153 a coaxially with the first gear wheel 153 a. The intermediate gear 153 d is connected to the second gear wheel 153 b. Additionally, the pickup rack 155 is connected to the intermediate gear 153 d. According to the above structure, the pickup rack 155 is moved in the same direction as the guide rack 151 by a distance approximately half as much as a moving distance of the guide rack 151.

Referring to FIGS. 2 and 5, a driving motor 171 is a driving source for driving the recording medium pickup module 130. The driving motor 171 is mounted at a predetermined fixed position.

A motor shaft 173 is connected to the driving motor 171 and is, for example, formed as a hollow pipe having a groove 173 a formed on an inner circumference thereof in a lengthwise direction, as shown in FIG. 5. A pickup module shaft 175 connected to the recording medium pickup module 130 is inserted in the motor shaft 173. A projection 175 a is formed on an outer circumference of the pickup module shaft 175 corresponding to the groove 173 a of the motor shaft 173. As the pickup module shaft 175 linearly reciprocates along the inner circumference of the motor shaft 173 in association with the linear motion of the recording medium pickup module 130, the projection 175 a is fit with the groove 173 a so that a rotational force of the motor shaft 173 is transmitted to the recording medium pickup module 130.

The operation of the document feeder according to the exemplary embodiments of the present invention is explained below.

Referring to FIGS. 2 and 4, first, the guide 110 is drawn in a direction shown by a dashed arrow by a distance greater than a width of the recording medium. The guide rack 151 is moved in the dashed-arrow direction, and the first gear wheel 153 a is rotated clockwise along the dashed-arrow direction. Accordingly, the second gear wheel 153 b disposed above the first gear wheel 153 a is rotated clockwise in the dashed-arrow direction. Also, the intermediate gear 153 d meshed with the second gear wheel 153 b is rotated counterclockwise along the dashed-arrow direction. As a result, the pickup rack 155 is linearly moved in the same direction as the guide rack 151 along the dashed-arrow direction.

Next, plural sheets of the recording medium are stacked in the recording medium supply tray 101, and the guide 110 is pushed in a direction shown by a solid arrow, thereby arranging the width of the recording medium. Therefore, the first gear wheel 153 a is rotated counterclockwise along the solid-arrow direction, the second gear wheel 153 b disposed above the first gear wheel 153 a is also rotated counterclockwise in the solid-arrow direction, and the intermediate gear 153 d meshed with the second gear wheel 153 b is rotated clockwise along the solid-arrow direction. As a result, the pickup rack 155 meshed with the intermediate gear 153 d is linearly moved in the same direction as the guide rack 151 along the solid-arrow direction.

The recording medium pickup module 130 is thus moved to a position appropriate for pickup of the recording medium, for example, in the middle of the width of the recording medium.

During the above operation, the pickup rack 155 moves by a distance approximately half as much as the moving distance of the guide rack 151 because the second pitch circle diameter D2 of the second gear wheel 153 b is approximately half of the first pitch circle diameter D1 of the first gear wheel 153 a. As a consequence, the recording medium pickup module 130 is disposed approximately in the middle of the recording medium.

Positioning of the recording medium pickup module 130 is not limited to the middle of the width of the recording medium as described above, but the recording medium pickup module 130 may be positioned at other locations. Also, although the recording medium pickup module 130 is moved in the same direction as the guide rack 151 according to this exemplary embodiment, the present invention is not so limited. For example, the recording medium pickup module 130 may be moved in the opposite direction to the guide rack 151. An initial position of the recording medium pickup module 130 is set differently to account for movement in opposite directions of the recording medium pickup module 130 and the guide rack 151.

While the recording medium pickup module 130 is linearly moved as described above, the pickup module shaft 173 connected to the recording medium pickup module 130 is slid along the inner circumference of the motor shaft 171.

Because the projection 173 a of the pickup module shaft 173 is inserted in the groove 171 a formed on the inner circumference of the motor shaft 171, the pickup module shaft 173 is rotated as the motor shaft 171 rotates, thereby performing the pickup of the recording medium.

In a document feeder according to exemplary embodiments of the present invention, the recording medium pickup module is moved in association with the movement of the guide that arranges the width of the recording medium, so that the recording medium pickup module may be placed at the optimum position for picking up the recording medium.

According to the above, oblique or skewed feeding of the recording medium that may be caused due to the unevenly applied force for picking up the recording medium is substantially prevented.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. 

1. A document feeder of an image forming apparatus, comprising: a guide that arranges a width of at least one recording medium; a recording medium pickup module that picks up the at least one recording medium; and a recording medium pickup module shifting unit that shifts the recording medium pickup module in association with movement of the guide.
 2. The document feeder of claim 1, wherein the recording medium pickup module includes a guide rack connected to the guide; a pinion unit supporting reciprocating motion of the guide rack; and a pickup rack engaged with the pinion unit that linearly reciprocates substantially in parallel with the guide rack, and that is connected to the recording medium pickup module.
 3. The document feeder of claim 2, wherein the guide rack and the pickup rack are moved in substantially the same direction.
 4. The document feeder of claim 3, wherein the pickup rack is moved by a distance approximately half of a moving distance of the guide rack.
 5. The document feeder of claim 4, wherein the pinion unit includes a first gear wheel having a first pitch circle diameter; a second gear wheel having a second pitch circle diameter; and an intermediate gear connected to the second gear wheel and having a third pitch circle diameter.
 6. The document feeder of claim 5, wherein the first gear wheel is connected with the guide rack; and the intermediate gear is connected with the pickup rack.
 7. The document feeder of claim 5, wherein the second pitch circle diameter is approximately half of the first pitch circle diameter.
 8. The document feeder of claim 7, wherein the third pitch circle diameter is approximately equal to the second pitch circle diameter.
 9. The document feeder of claim 8, wherein the first gear wheel is connected with the guide rack; and the intermediate gear is connected with the pickup rack.
 10. The document feeder of claim 2, wherein a driving motor that drives the recording medium pickup module; a motor shaft connected with the driving motor; and a pickup module shaft connected with the recording medium pickup module for transmission of a rotational force from the motor and connected to the motor shaft to substantially linearly move with respect to the motor shaft.
 11. The document feeder of claim 10, wherein the motor shaft is substantially hollow to receive the pickup module shaft therein.
 12. The document feeder of claim 11, wherein the motor shaft has a groove formed on an inner circumference thereof in a lengthwise direction; and the pickup rack module shaft has a projection extending outwardly therefrom corresponding to the motor shaft groove.
 13. The document feeder of claim 2, wherein the recording medium pickup module is placed substantially in the middle of the width of the recording medium.
 14. The document feeder of claim 2, wherein the guide rack and the pickup rack are moved in substantially opposite directions.
 15. The document feeder of claim 5, wherein the second gear wheel is coaxially aligned with the first gear wheel.
 16. A document feeder of an image forming apparatus, comprising: an adjustable guide movable to receive a width of at least one recording medium; and a recording medium pickup module to pick up the at least one recording medium, the recording medium pickup module being movable in response to movement of the adjustable guide.
 17. A document feeder of an image forming apparatus according to claim 16, wherein a guide rack is connected to the adjustable guide; a pickup rack is connected to the recording medium pickup module; and a pinion unit movably connects the guide rack to the pickup rack such that movement of the adjustable guide results in movement of the recording medium pickup module.
 18. A document feeder of an image forming apparatus according to claim 17, wherein the guide rack and the pickup rack are moved in substantially the same direction.
 19. A document feeder of an image forming apparatus according to claim 18, wherein the pickup rack is moved by a distance approximately half of a moving distance of the guide rack.
 20. A document feeder of an image forming apparatus according to claim 17, wherein the pinion unit includes a first gear wheel having a first pitch circle diameter; a second gear wheel having a second pitch circle diameter; and an intermediate gear connected to the second gear wheel and having a third pitch circle diameter.
 21. A document feeder of an image forming apparatus according to claim 20, wherein the first gear wheel is connected to the guide rack; and the intermediate gear is connected to the pickup rack. 